A pulsation damper is added to a fuel rail in a gasoline port injection system used widely in prior art in order to absorb injection pulsation and pump pulsation. However, pulsation dampers are expensive per se and may result in a cost increase due to the requirements of a large number of components, and cause a new problem in ensuring installation space. Fuel rails provided with an absorbing wall surface as shown in patent documents 1 and 2 are already well-known, for providing a pulsation reducing effect without using a pulsation damper.
A flat cross section or incurved cross section of a fuel rail is necessary to form this kind of absorbing wall, having good formability and made of a material having a relatively low hardness in order to form it into such a cross sectional shape. In recent years, improvement of the injection rate is required by changing fuel to increase fuel pressure in order to improve fuel efficiency and due to more stringent emission regulations. However, the conventional fuel rails for port injection as shown in patent documents 1 and 2 cover relatively low fuel pressures of 400 kPa or lower.